Bath tubs and other water-proof vessels, etc. in a bathroom usually use fiber-reinforced plastics (FRP) as molding materials. However, such molded products are difficult to break down or burn off when they become waste products. The treatment of these waste products becomes a social problem. Therefore, processes for effective recycling of waste FRP have been researched in recent years.
For example, one prior art method involves using a first mold and a second mold. It is known that there is a temperature difference between the first mold and the second mold. The molding material, which comprises thermosetting plastic resin and contains no waste FPR, freezes on the first mold at the high temperature side and the first layer forms by combining the first mold and the second mold. In one prior art process, the molded resin product having the first layer and second layer is prepared by coarsely crushing the frozen molded waste FRP into FRP coarse powder in advance, freezing the molding material obtained by incorporating a given amount of the FRP coarse powder into an unfrozen thermosetting resin on the first layer, and combining the molds (Refer to the “Patent Literature” 1- JP 8-244055). In the preparation of the second layer, the molding material containing FRP coarse powder is frozen and the molds are combined in the stage when the side of the second mold in the first layer has not fully frozen.
However, the process as disclosed in Patent Literature 1 for making the molded resin product has the disadvantage of too many procedures since a second molding procedure is needed which forms the second layer on the first layer using a molding material containing FRP coarse powder after preparing the first layer using the thermosetting plastic resin containing no FRP coarse powder before the first layer fully freezes. There also exists the problem of separation of the first layer from the second layer since different procedures are used in molding the two layers.
As a surface treatment, an outer protection layer is coated after the surface of the molded resin product is coated with a color sanding sealer, and a UV coating is then carried out at last. The UV coating generally possesses an excellent waterproof property and one UV coating is enough for the waterproof property. However, waterproof performance should further be improved when the product is used as a material of the floor and wall of a bathroom. Therefore, a coating with a certain thickness must be formed on the surface of the molded resin product, and the thickness of the coating formed by one UV coating is limited.